Stephen c



(No Model.)

S. G. DUVAL.

GRAPHIC NEGATIVE FILM FOR PHOTOGRAPHIO PRINTING.

No. 345,220. I Patented July 6, 1886.

WITNESSES: S INVENTOR: Jwwws BY fi ATTORNEYS.

N. FFIER$. Fhulc-Lilhogmphor. Washinghm. n. c.

I N TED STATES PATENT OFFICE.

STEPHEN O. DUVAL, OF NEW YORK, N. Y.

GRAPHIC NEGATIVE FILIVl FORPHOTOGRAPHIC PRINTING.

SPECIFICATION forming part of Letters Patent No. 345,220, date-d July 6,1856.

Application filed July 11, 1885.

I0 @ZZ whom it may concern:

Be it known that I, STEPHEN O. DUVAL, of the city, county, and State ofNew York, have invented a new and Improved Graphic Negative Film forPhotographic Printing, of

which the following is a full, clear, and exact description.

My invention is designed more especially to be used in connection withthe so-called blue process paper for photo-printing or reproducingoriginal drawings or writing and the invention consists of a transparentfilm or surface rendered opaque with substances, substantially ashereinafter described, the same containing coloring-matter, so that whenthe surface is written, drawn, or engraved upon with a suitableinstrument, and the opaque coating thus removed in lines from thetransparent sheet or film, the lines will be clearly apparent to theartist, thus enabling him to see his work as it progresses withouthaving to hold the film up to the light.

Reference is to be had to the accompanying drawing, forming part of thisspecification, in which the figure is a perspective view of atransparent shect'or film partly coated upon one surface according to myinvention.

A represents a transparent sheet, preferably of gelatine, and B is anopaque coating, composed of a dark or colored adhesive substance orvarnish and some powdered sub stance covering one surface of the sheet.

In applying the coating B to the sheet A, I first coat the sheet uponone surface with a thin varnish composed of asphaltum, beeswax,

and turpentine, adding sufiicient lamp-black Serial No. 171,398. (Nomodel.)

ment or engravers tool the coated surface may be drawn, written, orengraved upon, the removal of the coating indicating the Work. Thecoating thus being removed by the instrument, the sheet will be madetransparent at all points along the path of the instrument, while at allother points it will remain opaque, so that the sheet may bephoto-printed from or used as a medium for graphic purposes by anymethod of photographic or photolithograph reproduction.

In writing or drawing upon the sheet the color of the varnish greatlyfacilitates the work, as it shows a dark line as the instrument passesover the coating, enabling the artist to plainly see his work withoutholding the sheet up to the light.

The sheets may be used as the medium for snaking photolithographs directupon the stone, for making zinct-ypes, gelatiue and electrot-ypcs, asthe film answers the purpose of either positive or negative, and beingmore pliable and elastic than any other substance used forthis purposebetter contact can be ob tained and better work produced, and inprinting with the blue process it gives blue lines upon a white ground,and a superior rcproduction can be made.

Having thus described my invention, what I-claim as new, and desire tosecure by Letters Patent, is-

l. The transparent sheet A of gelatine rendered opaque by the coating 13of asphaltum, beeswax, and turpentine applied to the surface of thesheet, substantially as described.

2. The transparent sheet A of gelatine rendered opaque by a coating, 13,composed of dark or colored varnish or adhesive substance, consisting ofasphaltum, beeswax, turpentine, and lamp-black or other coloring-matter,and a metallic powder applied to the varnish or adhesive substance,substantially as and for the purposes described.

STEPHEN O, .DUVAL.

Witnesses:

W. F. GRANT, CHAS. O. SOHOENEOK.

